HSPC117 is the essential subunit of a human tRNA splicing ligase complex.

February 11, 2011

Identification of the tRNA ligase HSPC117. (A) siRNAs can be used as a substrate for human RNA ligase activity. siRNA duplexes are efficiently ligated in HeLa cell extracts only in case they display a phosphate group at their 3’ end and a hydroxyl group a

Transfer RNAs (tRNAs) are absolutely necessary to translate the genetic code into proteins required for life. In humans, some tRNAs are synthesized in an immature form containing an intervening sequence that has to be removed by sequential cleavage and joining reactions. Although the factors carrying out the cleavage reactions are already known for several years, the so-called tRNA ligase joining the tRNA exon pieces together remained unknown. We applied chromatographic techniques to purify proteins required for the joining reaction from the complex cell extracts able to process tRNA precursors into their mature form. After several rounds of purification we arrived at a mixture of ca. 100 proteins which we could examine in greater detail. One of those, called HSPC117, proved to be the essential factor for the described joining reaction as we were able to demonstrate by affinity purification and RNAi-mediated inactivation experiments.

>>link to article on Science website

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